Rival Arms match-grade precision drop-in barrel with 6 groove rifling, low temperature vacuum PVD coating creates a durable barrier against wear and tear even in the harshest environments, BORSLICK Boron Nitride DCD (Dynamic Compound Deposition) inner bore treatment resists heat and carbon buildup and target crowned muzzle. Threaded barrels and protectors use 1/2"-28 threads for comparability with after market accessories like suppressors and compensators. All threaded barrels include a color matching Rival Arms thread protector. No gunsmithing required. Barrels for Glock are compatible with both 3rd and 4th generation.